4,070 research outputs found
The role of bipartite structure in R&D collaboration networks
A number of real-world networks are, in fact, one-mode projections of
bipartite networks comprised of two types of nodes. For institutions engaging
in collaboration for technological innovation, the underlying network is
bipartite with institutions (agents) linked to the patents they have filed
(artifacts), while the projection is the co-patenting network. Projected
network topology is highly affected by the underlying bipartite structure,
hence a lack of understanding of the bipartite network has consequences for the
information that might be drawn from the one-mode co-patenting network. Here,
we create an empirical bipartite network using data from 2.7 million patents.
We project this network onto the agents (institutions) and look at properties
of both the bipartite and projected networks that may play a role in knowledge
sharing and collaboration. We compare these empirical properties to those of
synthetic bipartite networks and their projections in order to understand the
processes that might operate in the network formation. A good understanding of
the topology is critical for investigating the potential flow of technological
knowledge. We show how degree distributions and small cycles affect the
topology of the one-mode projected network - specifically degree and clustering
distributions, and assortativity. We propose new network-based metrics to
quantify how collaborative agents are in the co-patenting network. We find that
several large corporations that are the most collaborative agents in the
network, however such organisations tend to have a low diversity of
collaborators. In contrast, the most prolific institutions tend to collaborate
relatively little but with a diverse set of collaborators. This indicates that
they concentrate the knowledge of their core technical research, while seeking
specific complementary knowledge via collaboration with smaller companies.Comment: 23 pages, 12 figures, 2 table
On the Mechanism of Townsend Avalanche for Negative Molecular Ions
Time projection chambers drifting negative ions (NITPC) instead of electrons
have several advantages. A NITPC can operate at very high reduced drift fields
without diffusion runaway, and the readout digitization sampling rate
requirement is considerably relaxed due to the low drift speed of negative
ions. The initiation of Townsend avalanches to allow gas gain in these devices
has not been understood until now. It is shown here that the avalanche in low
pressure CS vapor is most likely initiated by collisional detachment of the
electron from the negative molecular ion. In mixtures of Nitromethane vapor
with CO the mechanism appears to be more complex
Explicit approximate controllability of the Schr\"odinger equation with a polarizability term
We consider a controlled Schr\"odinger equation with a dipolar and a
polarizability term, used when the dipolar approximation is not valid. The
control is the amplitude of the external electric field, it acts non linearly
on the state. We extend in this infinite dimensional framework previous
techniques used by Coron, Grigoriu, Lefter and Turinici for stabilization in
finite dimension. We consider a highly oscillating control and prove the
semi-global weak stabilization of the averaged system using a Lyapunov
function introduced by Nersesyan. Then it is proved that the solutions of the
Schr\"odinger equation and of the averaged equation stay close on every finite
time horizon provided that the control is oscillating enough. Combining these
two results, we get approximate controllability to the ground state for the
polarizability system
A benign, low Z electron capture agent for negative ion TPCs
We have identified nitromethane (CHNO) as an effective electron
capture agent for negative ion TPCs (NITPCs).
We present drift velocity and longitudinal diffusion measurements for
negative ion gas mixtures using nitromethane as the capture agent.
Not only is nitromethane substantially more benign than the only other
identified capture agent, CS, but its low atomic number will enable the use
of the NITPC as a photoelectric X{}-ray polarimeter in the 1{}-10 keV band
Bourdieu, networks, and movements: Using the concepts of habitus, field and capital to understand a network analysis of gender differences in undergraduate physics
Current trends suggest that significant gender disparities exist within
Science, Technology, Engineering, and Mathematics (STEM) education at
university, with female students being underrepresented in physics, but more
equally represented in life sciences (e.g., biology, medicine). To understand
these trends, it is important to consider the context in which students make
decisions about which university courses to enrol in. The current study seeks
to investigate gender differences in STEM through a unique approach that
combines network analysis of student enrolment data with an interpretive lens
based on the sociological theory of Pierre Bourdieu. We generate a network of
courses taken by around 9000 undergraduate physics students (from 2009 to 2014)
to quantify Bourdieu's concept of field. We explore the properties of this
network to investigate gender differences in transverse movements (between
different academic fields) and vertical movements (changes in students'
achievement rankings within a field). Our findings indicate that female
students are more likely to make transverse movements into life science fields.
We also find that university physics does a poor job in attracting high
achieving students, and especially high achieving female students. Of the
students who do choose to study physics, low achieving female students are less
likely to continue than their male counterparts. The results and implications
are discussed in the context of Bourdieu's theory, and previous research. We
argue that in order to remove constraints on female student's study choices,
the field of physics needs to provide a culture in which all students feel like
they belong.Comment: 23 pages, 6 figures, 1 tabl
The look-ahead effect of phenotypic mutations
The evolution of complex molecular traits such as disulphide bridges often
requires multiple mutations. The intermediate steps in such evolutionary
trajectories are likely to be selectively neutral or deleterious. Therefore,
large populations and long times may be required to evolve such traits. We
propose that errors in transcription and translation may allow selection for
the intermediate mutations if the final trait provides a large enough selective
advantage. We test this hypothesis using a population based model of protein
evolution. If an individual acquires one of two mutations needed for a novel
trait, the second mutation can be introduced into the phenotype due to
transcription and translation errors. If the novel trait is advantageous
enough, the allele with only one mutation will spread through the population,
even though the gene sequence does not yet code for the complete trait. The
first mutation then has a higher frequency than expected without phenotypic
mutations giving the second mutation a higher probability of fixation. Thus,
errors allow protein sequences to ''look-ahead'' for a more direct path to a
complex trait.Comment: Submitted to "Genetics
Stencel Aero Engineering Corporation v. United States: An Expansion of the Feres Doctrine to Include Military Contractors, Subcontractors, and Suppliers
In Feres v. United States, military personnel were denied the right to sue the United States under the Federal Tort Claims Act for injuries sustained incident to military service. A case recently decided by the United States Supreme Court, Stencel Aero Engineering Corporation v. United States, expanded the scope of the Feres Doctrine to include third party government contractors and suppliers seeking indemnity from the United States on claims by active-duty service personnel. This Note examines the recent Stencel decision and considers the effect of this decision upon the indemnity claims of private parties sued as joint tortfeasors with the government
Putting a human face to severe traumatic brain injury research : a review of neuropsychological rehabilitation, obsessive-compulsive disorder and caregiver burden with respect to the case of BP : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Psychology at Massey University
The following thesis is a review of several issues relating to severe brain injury. The theories and research literature were also paired with the case study of a young man who had suffered a severe TBI three years ago, and the outcomes and rehabilitation that he has faced since and continued to face. The case study and theory can be read separately, but it is together that they may help to put a human face on the TBI literature. Rehabilitation principles and theories are described in order to present a picture of an ideal rehabilitation plan, and then contrasted by the case study to demonstrate the difficulties that are inherent in severe TBI. Despite careful adherence to rehabilitation principles, the rehabilitation process remains difficult and lengthy. The research literature regarding obsessive-compulsive disorder and TBI are discussed in reference to aspects of the current case study and impulse control disorders in general. The caregiver burden research literature, particularly with regard to that of TBI, is also reviewed, with reference again to the current case study. A plea is made for more flexible, functionally-relevant rehabilitation models, that attempt to take into account the true complexities involved in severe TBI rehabilitation. The use of case studies in future TBI research, along with the larger-sampled empirical studies, may aid our understanding of TBI and its rehabilitation from a more human real-life perspective
Alien Registration- Dion, Catherine J. (Westbrook, Cumberland County)
https://digitalmaine.com/alien_docs/20774/thumbnail.jp
- …